Abstract: Three-dimensional dynamic response of a circular lining tunnel surrounded by a full-space saturated soil to a harmonic point load acting in the radial direction is investigated. The lining is modeled as a cylindrical shell of infinite length; and the soil is modeled as a saturated poroelastic medium using Biot’s theory. Two kinds of potential functions are introduced to represent the displacements of the soil skeleton and the excess pore fluid pressure; and the modified Bessel equations are utilized to obtain the expressions of the potentials function. According to boundary conditions, the analytical solutions of displacements of lining and soil and pore pressure are derived in frequency-wave number domain. Finally, the time-space domain solutions of the dynamic responses are obtained by inverse Fourier transformation. The effects of load vibration frequency and soil permeability on displacement and pore pressure responses are investigated. Numerical results show that the displacement response of saturated soil is significantly different from that of single phase elastic soil. As the load vibration frequency increasing, the displacement amplitudes of soil and tunnel decrease, while the pore pressure amplitude increases. The displacement and pore pressure amplitudes of soil decrease as the soil permeability getting better.

Key words: harmonic point load, lining tunnel, saturated soil, dynamic response